This unit provides a nucleus of ongoing inquiry where investigators can benefit from their mutual association and be available to exploit opportunities to solve problems in psychiatric epidemiology. The unit developed initially on the basis of two field stations located in laboratory populations (Washington Heights Health District and Dutchess County, New York) (and with the closing of those two laboratories will be based in The Johns Hopkins School of Hygiene's Department of Mental Hygiene). The established system for screening the published literature and profiling the data published (PELP) will be transfered to new locus. Fruitful collaborations with Prof. Olle Hagnell, Department of Psychiatry, Lund, Sweden, will be continued. These data have demonstrated within the last few months that the prevalence of chronic brain syndromes among the elderly rose several fold between 1947 and 1957 and that this rise can be attributed to the differential effect of mortality reductions, the sick being much more affected than the well. Arrangements have been made with Prof. Olle Hagnell for Prof. Maurice Satin to spend two months in Lund preparing the 25 year follow-up data for automatic processing. The Dutchess County Register has already been discontinued but the original file will be microfilmed and transferred. Data tapes will also be transferred so that subsequent analyses can be made. The epidemiological issues which will be attacked in the future will take full advantage of the opportunities afforded in the Baltimore context. Related specialised personnel exist in other departments of Johns Hopkins University. Populations for research have developed both in Washington County, Md. and in Columbia, Md. (in connection with the Health Services Research and Development Center directed by Sam Shapiro). Preliminary discussions have taken place with colleagues associated with these two populations.